40 MEMBERS OF INSECTS. 



the bee, where the simple eyes are three in number, 

 and placed in a triangle. 



The upper portion of a bee, showing the two compound eyes 

 with their facettes at the base of the jointed ears : together with 

 the three simple eyes in form of a triangle on the crown. 



We do not meet with simple eyes in all insects, but 

 no adult insect is without compound eyes. The num- 

 ber of simple eyes is usually three. Each is composed 

 of, 1. an outer membrane, hard, transparent, and 

 formed of a single piece ( l ) ; 2. a layer of a viscous or 

 clammy substance ( 2 ), immediately behind the first, 

 which determines the colour of the eye, being black 

 in bees, white in crickets and grasshoppers, and red, 

 yellow, or green in some caterpillars; 3. a rather 

 thick membrane ( 3 ), seemingly composed of a tissue of 

 net- work, whose meshes are very closely set ; and 4. 

 a nerve from the ganglion of the head, very small, 

 which penetrates to the inside of the outer mem- 

 brane, where it spreads out. 



Compound, composite, shagreened, or facetted 

 eyes, are so named from being made up of a great 



(3) In Latin, Cornea. (2) In Latin, Pigmentum. 



(3) In Latin, Chor aides. 



